John p



J. P. NEWMAN 2,733,621

ROTARY IMPACT WRENCH WITH OVERLOAD RELEASE MEANS Feb 7, 1956 Filed Oct. 3l, 1952 Joy/v P. Nia/MMV, JNVENTOR.

TTNEYS United States Patent ROTARY llVIPACT WRENCH WITH OVERLOAD RELEASE MEANS John P. Newman, Alhambra, Calif.

Application October 31, 1952, Serial No. 317,985 'K10 claims. (ci. s1`sz.3)

This invention relates to a new and improved form of impact wrench. s

One of the principal objects of this invention is to provide a power driven impact wrench having novel means for intermittently connecting andi disconnecting the driven member from the power driven drive shaft.

Another object of this invention is to provide a power driven impact wrench which is-of an extremely simple lconstruction permitting an inexpensive and rugged strncture.

Another object of this invention is to provide an impact wrench having novel means for the quick and easy adjustment of the magnitude of the successive impacts delivered by the wrench.

Another object of this invention-is toprovide a power driven impact wrench including a rubber-like sleeve member which performs the dual functions of storage of ice Figure 3 is a sectional view taken substantially on the i line 3-3 of Figure 1.

, electric motor 10. Electrical current for the motor is transmitted through the cable 14 which depends from the underside of the handle portion 12. A switch lever 15 may also be mounted on the handle 12 for reversing the direction of rotation of the shaft of the motor 10 when desired. It is to be understood that an air driven motor may be substituted for the electric motor if desired,

energy for the repeated blows or impacts and actuation of the mechanism for intermittently connecting and disconnecting the driven member from the power driven shaft. s

Briefly this invention comprises a power driven impact wrench including a driven hammer and an anvil member operated upon by `the hammer, the hammer being connected to the drive shaft by means of a rubber-like sleeve encircling the shaft and which is adapted to be placed in torsion to store energy. It has been found that a rubberlike sleeve of the type utilized in the impact'wrench of this invention, when placed in torsion elongates, the degree of elongation being dependent upon the amount Vof twisting undergone by the sleeve. This phenomenon is utilized in causing the hammer to be intermittently disengaged from and engaged with the anvil member. As the rubber-like sleeve elongates, it moves the hammer in a direction away from the anvil member until the hammer becomes disengaged therefrom, whereupon the energy stored in the rubber-like sleeve is released to cause a rapid rotation of the rubber-like sleeve and hence, of the hammer. The rubber-like sleeve thereupon returns to its original dimensions and thereby moves the hammer to engage with the anvil member, causing the hammer to strike the anvil member a sharp blow. Adjustment means are also provided whereby the elongation of the rubberlike sleeve required to disengage the hammer from the anvil member may be varied, and hence whereby the 4amount of energy stored in the rubber-like sleeve and the resultant magnitude of the hammer blows may be varied.

Other objects and advantages of this invention it is believed will be apparent from the following detailed description of a preferred embodiment thereof when read in connection with the accompanying drawings.

In the drawings:

Figure 1 is a side elevation, partly in section, of an impact wrench embodying the invention.

Figure 2 is a fragmentary side elevation similar to Figure l, but illustrating the hammerin disengaged position. i

since the particular type of power means employed for turning the drive shaft does not constitute an important part of the invention.

Reduction gearing may be provided for driving the drive shaft 16 from the motor shaft 17, and as shown in the drawings .this gearing may include the small pinion gear 19 on the counter shaft 20. A pinion 21 alsoixed on the counter shaft 20 engages the larger driven gear 22a which is keyed to the drive shaft 16 by means of the key 23. The housing 11 provides suitable bearings for the motor shaftv 17. Secured to the forward end of the housing is a cover member 22 provided with a central bearing 23a for the Vrearward end of the drive shaft 16. 'As shown, the drive shaft is provided with a shoulder member 16a which abuts against the face plate of the bearing 23a, preventing rearward thrust of the drive shaft.

A cylindrical housing extension or shell 24 is threadedly engaged at the rearward end thereof withinternal threads on the cover member 22. A lock nut element 25 is provided to maintain the housing extension 24 in the desired position with respect to the cover member V22. T he forward projecting end of the housing extension or shell 24 is connected by any suitable means to the bearing sleeve sleeve 28. The drive shaft 16 extends axially through the shell 24 and its outer end 29 extends intothe bearing sleve 28. A resilient rubber-like drive sleeve 30 encircles the drive shaft 16 for a portion of the length thereof and is connected at its forward end in driven relationship with the drive shaft 16 by means of thepin connection 31. The outer ends of the pin 31 extend through a cylindrical reinforcement element 32.` j The rearward end of the sleeve 30 is connected by meansgof the pins 33 to the rearward end of a hammer member 34 which is rotatably mounted within the shell 24. The pins 33 extend through a cylindrical reinforcement element 35. A

bearing member 36 extends about the inner periphery of the rearward end of the sleeve 30, and contacts the drive shaft 16 to permit relative rotation between the drive shaft 16 and the vrearward end of the sleeve 30. A bearing member, 37 is secured to the drive shaft 16 and the sleeve 30 by means of the pin 31 and is provided with a cylindrical bearing -surface 3S rotatably supporting the forward end of the hammer 34. It will be noted that since the sleeve 30 is constructed of rubber or rubber-like material, the rearward end of the sleeve and also `the hammer may be driven by the shaft 16 but arecapable of relative angular movement with respect thereto.

The hammer 34 is provided at its forward end with a pair of protruding dogs 4t) disposed 180 apart. A driver member 41 is rotatably mounted within the bearing sleeve 2S and is provided with a flange portion `42 received within the shell 24 and forming an anvil member having a pair of oppositely disposed projections 44, each having radial driving jaw surfaces 45 and 46. From an inspection of Figures 1 and 3 it Will be apparent that in I 3 the normal driving relationship, the dogs 40 contact the respective jaw surfaces 4S of the projections 44.

The forward end of the driver member 41 projects from the bearing sleeve 23 and is providedv with a non-circular portion 50, which ordinarily is formed with a square cross section. A conventional socket member (not shown) provided with a square opening for the reception of the noncircular project 50 and also provided with the usual socket for reception of a nut or bolt head is adapted to be retained on the non-circular portion S0.

The driver member 41 is provided with a central counter bore 52, the end portion of which forms a bearing surface for the forward end of the drive shaft 16. A helical spring 54 is provided in thecounter bore 52 and is under compression to maintain theV ange member 42 in abutting relationship with the radial end face 53 of the bearing sleeve 23.

, In operation of the device embodying this invention, the drive shaft 16 is turned by the motor 10 through the reduction gearing described above. So long as no resistance to rotation is imposed by the socket member (not shown), the drive shaft 16, drive sleeve 30, hammer member 34, and driver member 41 all rotate as a unit with respect to the shell 24 and bearing sleeve 28. When resistance to rotation of the socket member (not shown) is encountered, such as for example, by the tightening of the nut or bolt (not shown) which is being operated upon, the driver 41 slows down relative to the drive shaft 16. The angularvelocity of the hammer 34, it being in driving engagement with the projections 44V of the driver 41, will likewise be reduced. In turn, the speed of rotation of the rearward end of the drive sleeve 30 will be reduced, since it is connected to the rearward end of the hammer 3,4. However, the forward end of the drive sleeve 30 is rigidly connected to the drive shaft 16 and hence this portion of the sleeve 30 will be rotated at a faster rate of speed than the rearward end thereof. TheV drive sleeve 30 will accordingly be twisted or placed in torsion an amount dependent upon the degree of relative movement between the hammer 34 and the drive shaft 16.

As the sleeve 30 is twisted the longitudinal dimension thereof increases causing the rearward end of the sleeve V to move relative to the drive shaft 16 and housing extension 24 in a rearward direction, thus also moving the hammer 34 in the same direction. This movement continues until the dogs 40 have been moved out of engagement with the jaw surfaces 45, as shown in Figure 2. l At this point, the sleeve 30 is freed of any forces tending toV maintain it in torsion, and the energy thereby stored in the sleeve isreleased, causing the rearward portion of the sleeve to be rotated rapidly at a speed greater than the speed of the drive shaft 16. With the release of this energy the longitudinal dimension of the sleeve 30 is reduced to the original magnitude as shown in Figure l., and the dogs 40 are again engaged with the jaw surfaces 45 of the anvil member. The hammer 34 has a relatively large mass and accordingly, the dogs 40 strike the anvil projections 44 with a sharp blow or impact. Continued resistance to rotation of the socket member (not shown) causes a repetition of the above described cycle ofstorage of energy in the sleeve 30, disengagement ofthe hammer from the anvil, release of the energy stored `in the sleeve and subsequent engagement of the hammer with the anvil together with the impact therebetween. When the socket member (not shown) is engaged in tightening a nut or bolt, the effect is to' apply two separate impacts for each revolution of the drive shaft 16. When Ythe nut reaches its final tightened position, the socket member and'driver Y 41 cease to rotate at all with the result that the hammer 34 comes to a stop and accelerates rapidly twice during each revolution of the drive shaft 16.

`If it is desired to remove a tightened nut from a bolt,

-or if it is desired to tighten a nut having left-hand threads,

the direction of rotation of the motor shaft 17 is reversed by means ofthe switch 15, and in such cases. the jaw surfaces 46 on the driver 41 become operative. The action of the rubber-like sleeve 30 is the same, however, with the exception that the sleeve is twisted in the opposite direction.

The magnitude of the individual impacts transmitted to the driver 41 may be varied by adjusting the position of the housing extension 24 relative to the cover member 22. This in turn causes a change in the position of the driver 41 and the anvil portion 42 relative to the hammer 34. It will thus be understood that by moving the housing extension 24 forwardly or rearwardly with respect to the cover member 22, the longitudinal amount of surface contact between the dogs 40 and the jaw surfaces 45 (or jaw surfaces 46, as the case may be) may be respectively increased or reduced. If a greater magnitude of impact is desired, the housing extension 24 and its related parts are moved in a rearward direction relative tol the cover membery 22., thus providing a greater longitudinal surface contact between the dogs 40 and jaw surfaces 45. Accordingly, a greater amount of twisting of the sleeve 30 is required in order tol cause an elongation of the sleeve sufficient to move the dogs out of contact with the jaw surfaces 45. Therefore, a greater amount of energy is stored in the sleeve 30 causing a greater impact. If, on the othre hand, a lesser impact is desired, the housing extension 24 is movedforwardly with respect to the cover member 22 anda smaller longitudinal surface contact between the dogs 40 and jawY surfaces 45 is provided, ultimately resulting in a lesser impact.

Having fully described the invention, it is to be understood that it is not intended to limit the invention to the details herein set forth, but it is of the full scope of the appended claims.

I claim:

l. In an impact wrench, thevcombination of a drive shaft, a driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, a cylindrical resilient driving member adapted to rotate the hammer member and driven from the drive shaft, cooperating means on said hammer member and sald driver member for releasable engagement therebetween, means for connecting to the hammer member the end of the resilient driving member most remote from the cooperating means, and other means for connecting the other end of the resilient driving member to the drive shaft so that upon relative rotational movement between the hammer member and the drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member out of engagement with the driver member.

2. In an impact wrench, the combination of a drive shaft, a driver member mounted coaxially of the drive shaft, power means for rotatingthe drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, a cylindrical resilient driving member adapted to rotate the hammer member and driven from the-drive shaft, cooperating means` on said hammer member and said driver member positioned forwardly of said resilient driving member for releasable engagement therebetween, means for connecting the forward end of the resilient driving member to the drive shaft, and other means for connecting the rearward end of the resilient driving member to the hammer member so that upon relativerotational movement between the Yhammer member and the drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member out of engagement with the driver member.

3. In an impact wrench, the combination of a drive shaft, a driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mountedv coaxially of the drive shaft, a resilient driving sleeve, `said sleeve having cylindrical Vinner and outer surfacesrcoaxial with the drive shaft,

to rotate the hammer member and driven from the drive shaft, cooperating means` on said hammer member and said driver member positioned forwardly of said resilient sleevefor releasable engagement therebetween, means for connecting the forward end of the resilient driving member to the drive shaft, and other means for connecting the rearward end of the resilient driving member to the hammer member so that upon relative rotational movement between the hammer member and the drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member out of engagement with the driver member. v v

4. In an impact wrench, the combination of a drive shaft, a driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, a cylindrical resilient driving member adapted to rotate the hammer member and driven from the drive shaft, cooperating means on said hammer member and said driver member for releasable engagement therebetween, means for connecting one end of the resilient driving member to the drive shaft, other means for connecting the other end of the resilient driving member to the hammer member so that upon relative rotational movement between the hammer member and the drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member out of engagement with the driver member, and means for adjusting the position of the hammer member relative to the driver member.

5. In an impact wrench, the combination of a drive shaft, a driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, a cylindrical resilient driving member adapted to rotate the hammer member and driven from the drive shaft, radial jaw surfaces on said hammer member and said driver member for releasable engagement therebetween, said hammer member and said driver member adapted to be disengaged by relative longitudinal movement thereof, means for connecting one end of the resilient driving member to the drive shaft, other means for connecting the other end of the resilient driving member to the hammer member so that upon relative rotational movement between the hammer member and the drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member longitudinally out of engagement with the driver member, and means for adjusting the longitudinal position of the hammer member relative to the driver member.

6. In an impact wrench, the combination of a housing, a drive shaft journaled at the rearward end thereof in said housing, an extension housing threadedly connected at the rearward end thereof to and coaxial with said housing, a driver member journaled in the forward end of said extension housing and having a bearing surface supporting the forward end of said drive shaft, a pair of circumferentially spaced projections extending rearwardly from said driver member, each projection having a pair of radial jaw surfaces, power means in said housing for rotatingthe drive shaft, a hammer member rotatably mounted in said extension housing and axial of the drive shaft,

said hammer member having at the forward end thereof a pair of protruding'dog members engageable with said radial jaw surfaces, a resilientdriving sleeve having cylindrical inner and outer surfaces coaxial with the drive shaft, said sleeve being interposed between the drive shaft and the hammer member, said resilient sleeve being adapted to rotate the hammer member and being driven from the drive shaft, a pin rigidly connecting the for-v ward end of said driving sleeve to the drive shaft, the rearward end of said driving sleeve being free to move relative to said drive shaft, and a second pin rigidly connecting the rearward end of the driving sleeve to said hammer member whereby upon relative rotationalmovement between the hammer member andthe drive shaft the driving sleeve is twisted and thereby elongated to move the hammer member dogs longitudinally out of engagement with the jaw surfaces of said driver member.

7. In an impactv Wrench, the combination of a drive shaft, a driver member, a pair of circumferentially spaced projections extending rearwardly from said driver member, each projection having a pair of radial jaw surfaces, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, said hammer member having at the forward end thereof apair of protruding dog members engageable with said radial jaw surfaces, a resilient driving sleeve having cylindricalf inner and outer surfaces coaxial with the drive shaft, said, sleeve being interposed between the drive shaft and the hammer member, said resilient sleeve being adapted to rotate the hammer member and being driven from the drive shaft, a pin rigidly connecting the forward end of said driving sleeve to the drive shaft, the rearward end of said driving sleeve being free to move relative to said drive shaft, and a second pin rigidly connecting the rearward end of the driving sleeve to said hammer member whereby upon relative rotational movement between the hammer member and the drive shaft the driving sleeve is twisted and thereby elongated to move the hammer member 'dogs longitudinally out of engagement with the jaw surfaces of said driver member.

8. In an impact wrench, the combination of a drive shaft, a driver member, a pair of circumferentially spaced projections extending rearwardly from said driver member, each projection having a pair of radial jaw surfaces, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, said hammer member having at the forward end thereof, a pair of protruding dog members engageable with said radial jaw surfaces, a resilient driving sleeve having cylindrical inner and outer surfaces coaxial with the drive shaft, said sleeve being interposed between the drive shaft and the hammer member, said resilient sleeve being adapted to rotate the hammer member and being driven from the drive shaft, a pin rigidly connecting the forward end of said driving sleeve to the drive shaft, the rearward end of said driving sleeve being free to move relative to said drive shaft, a second pin rigidly connecting the rearward end of the driving sleeve to said hammer member whereby upon relative rotational movement between the hammer member and the drive shaft the driving sleeve is twisted and thereby elongated to move the hammer member dogs longitudinally out of engagement with the jaw surfaces of said driver member, and means for adjusting the longitudinal position of the hammer member relative to the driver member.

9. In an impact wrench, the combination of a drive shaft, a tool driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, an elongated cylindrical resilient driving member adapted to rotate the hammer member and driven from the drive shaft, cooperating jaws on said hammer member and said driver member for releasable engagement therebetween, means for connecting the rear end of the resilient driving member to the drive shaft, and other means for connecting the front end of the resilient driving member to the hammer member so that upon relative rotational movement between the hammer member and the` drive shaft the resilient driving member is twisted and thereby elongated lto move the hammer member out of engagement with the driver member.

10. In an impact Wrench, the combination of a drive shaft, a tool driver member mounted coaxially of the drive shaft, power means for rotating the drive shaft, a hammer member rotatably mounted coaxially of the drive shaft, an elongated cylindrical resilient driving member adapted to rotate the hammer member and driven from the drive shaft, radial jaw surfaces on said hammer mem- Y drive shaft the resilient driving member is twisted and thereby elongated to move the hammer member longitudi- '\nally out of engagement with the driver member.

ReferenesCvited in the le o this patent,l

UNITED STATES 'PATENTS Pott July 28, 1936 Mevnier Nov. 24, 1936 Pott May 16, 1939 Fletcher Oct. 15, 1946 Shaft July 19, 1949 Barker et al Oct. 31, 1950 Newman Nov. 27, 1951 FOREIGN PATENTS Great Britain May 7, 1925 

